Alabama receives a variety of winter precipitation, even across the southern part of the state. A few degrees can mean the difference between a forecast with snow or a forecast with ice!

SnowFrozen precipitation that falls through a deep below-freezing atmospheric layer, often reaching the ground in the form of soft, white flakes.

SleetFrozen precipitation that falls through a shallow layer of warm air (above freezing) will partially melt. It will re-freeze into ice pellets as it re-enters a layer of air that is below freezing. Sleet usually bounces when it hits the surface and does not stick to objects. However, sleet can accumulate like snow and cause hazardous travel conditions.

Freezing RainThis occurs when frozen precipitation completely melts into rain as it falls through a deep layer of warm air (above freezing). As the rain re-enters the shallow layer of cold air near the surface, it will re-freeze on contact as it reaches the surface. Freezing rain will create a coating of ice on any object it comes contacts.

Accumulation of snow, sleet or freezing rain can create hazardous travel conditions. Sleet and freezing rain are VERY DANGEROUS, as the ice creates slick spots on roadways, causing motorists to quickly lose control of their vehicles. Bridges, overpasses and elevated surfaces are especially susceptible to icing. The weight of accumulating ice can quickly down trees and power lines.

Other Winter Terminology

FrostFrost is the formation of thin ice crystals on the ground (or other surfaces) in the form of scales, needles, feathers, or fans. Frost develops under conditions similar to dew, except the temperature falls below freezing (32°F). Frost primarily occurs as the result of radiational cooling, thus can occur at temperatures of 35 to 37°F in light wind and clear sky conditions when the wet bulb temperature is near freezing.

Black IceBlack ice is patchy (clear) ice on roadways or other transportation surfaces that cannot easily be seen. This ice is often a deadly driving hazard that is most prevalent during early morning hours, especially after snow melt has a chance to refreeze overnight.

Extreme Cold Terminology

Exposure to cold can cause frostbite or hypothermia and can become life-threatening. Infants and the elderly are most susceptible to the impacts of extreme cold. In the Deep South, freezing temperatures can cause severe damage to citrus fruit crops and other sensitive vegetation. Pipes may freeze and burst in poorly-insulated homes or those without heat.

Wind ChillThe combined effect of the air temperature and the wind speed on exposed skin. As wind speed increases, heat is carried away from the body at an accelerated rate, which caused body temperature to decrease. Humans and animals are both impacted by wind chill.

FrostbiteThis is the damage to body tissue caused by extreme cold. Frostbite causes a loss of feeling and a white or pale appearance to extremities (e.g. fingers, toes, ears or the tip of the nose). If symptoms are detected, seek medical attention immediately! A wind chill of -20°F will cause frostbite in just 30 minutes.

Regardless of the severity of the winter weather, you should be prepared in order to remain safe during winter storms.

Travel Safety and Preparedness Tips:

Check the latest weather information to avoid traveling during a winter storm! Minimize, avoid or postpone travel if at all possible. If travel is necessary during winter weather conditions, keep these tips in mind:

1. Let someone know your destination, route/alternate route and when you expect to arrive.
If your car gets stuck in snow, help can be sent to your route.

Winter weather impacts our forecast area covering southwest Alabama, southeast Mississippi and northwest Florida much differently than it does across the northern part of the United States. Accordingly, the criteria for winter weather products vary at each National Weather Service office. Here is a look at the criteria for the NWS Mobile area:

- WATCH PRODUCTS -WATCH = Be Alert!

Winter Storm Watch Potential for (a 50% or greater chance of)
Snow: accumulation of 2 inches or more in a 12 hour period OR
Sleet/Ice Pellets: accumulation of 1/2 inch or more OR
Freezing Rain/Drizzle: accumulation of 1/4 inch or more of ice OR
Combination of these
in the next 12-48 hours.

Wind Chill WatchPotential for wind chill values of -10°F or lower in the next 12-48 hours.

Freeze WatchPotential for light freezing temperatures (generally 28°F to 32°F) to pose a threat to new growth at the start and end of the growing seasons in spring and autumn (or after an extended period of unusually warm weather) within the next 24-48 hours. This product is issued to raise awareness for agricultural and gardening interests.

Hard Freeze WatchPotential for the minimum temperature to reach 20°F or colder across the area (not just a single/isolated location) within the next 24-48 hours. This type of freeze poses a threat to exposed water pipes, farm equipment and livestock (as well as automobile engine blocks and radiators if these temperatures persist for long periods).

- ADVISORY PRODUCTS -ADVISORY = Take Action!

NOTE: As of the 2017 Winter Season, NWS Offices no longer issue Freezing Rain Advisories. This legacy product is part of the consolidation of winter weather products and is now covered by a Winter Weather Advisory.

Winter Weather Advisory Issued when
Snow: accumulation of less than 2 inches in a 12 hour period OR
Sleet/Ice Pellets: accumulation of less than 1/2 inch OR
Freezing Rain/Drizzle: accumulation of less than a 1/4 inch OR
Combination of these.
Issued up to 36 hours in advance of the event.

Wind Chill AdvisoryWind chill values of -9°F to 10°F are expected.

Frost AdvisoryA frost is expected at the start and end of the growing seasons in spring and autumn within the next 12-24 hours. The product is issued to alert agricultural interests and growers to the potential of frost burn on sensitive outdoor plants.

- WARNING PRODUCTS -WARNING = Take Action!

Winter Storm WarningIssued when there is a 80% or greater chance of
Snow: accumulation of 2 inches or more in a 12 hour period OR
Sleet/Ice Pellets: accumulation of 1/2 inch or more is imminent OR
Combination of these.
Issued up to 36 hours in advance of the event.

Ice Storm WarningSignificant ice accumulations of 1/4 inch or more are expected.

Blizzard WarningSustained winds (or frequent gusts) of 35mph or greater are expected to be accompanied by falling and/or blowing snow, reducing visibility to less than 1/4 mile for 3 hours or more.

Wind Chill WarningWind chill values of -10°F or lower are expected.

Freeze WarningLight freezing temperatures (generally 28°F to 32°F) are expected to pose a threat to new growth at the start and end of the growing seasons in spring and autumn (or after an extended period of unusually warm weather) within the next 24 hours.

Hard Freeze WarningMinimum temperature is expected to reach 20°F or colder across the area (not just a single/isolated location) within the next 24 hours.